M42 radiator swap complete!

[White325is]

when I did my M42 rad swap on my M20 I just got another one of the metal pipes that run across the front of the motor. Cut the ends off of it and welded them together.
Took the stock M20 hose and cut a piece out of the middle and slipped my welded piece in the middle and tossed some clamps on it.
I could find a hose to fit and I went through 3 different stores to find one.

[SpecM]

seems to me that if you trimmed the engine side a little (like 1/4 in) it would take some stress of that kinked point

sorry I can't get to more info... my store (where all my catalogues are) closed today (snow!)

[vlad]

Levent did this swap and he knows exactly what hose to use, it's OEM
PM him for more info

[Naplm00]

Levent did this swap and he knows exactly what hose to use, it's OEM
PM him for more info

huh thats wired the last pic I saw of hism, the hose was kinked worse than mine..I'll PM him

[ZM Blue Devil]

where do you see the kink?

[Naplm00]

never mind look pretty good

[SpecM]

OK guys, spill the beans

what hose is it?

[Naplm00]

L is goin to text me the last seven of the car it came from.

I think it was a M20 equipped touring with manual trans and no AC from the factory. Hence a smaller rad with the same thermo housing.


I did some diggin in realoem and found 3 versions; one marked with nothing, one marked for cars with AC and one marked for cars with "tropical package"

I'm guessing it is the first, I am just waiting on him to confirm

[ZM Blue Devil]

I need to double check the receipts but its either...

11531722218

or


11531722217

[Naplm00]

top one is a stock hose for an eta

bottom one is a touring car hose WITH AC...if it was a 11531722216..it would be WITHOUT Ac

[Jand3rson]

I'm unbelievably stoked about this. I can't wait to get my hands on one and get this mod done!

[Naplm00]

its a great time to do a T belt, WP and front engine gaskets too if you need it

THe whole reason I even started this thing was because I needed to change out that incorrect water pump.

At some point today Ill do the write up sans pics

[browntown]

if only this worked for m30 swaps.

[b*saint]

I have a m42 radiator for sale if anyone wants it to do this mod.

[Naplm00]

M42 Radiator swap
This how to is for those who want to remove the clutch fan and AC far and condenser. If you want to keep these parts then disregard the extra steps. The mod can be done keeping these components functional. Early model cooling map want to swap to late model water pumps and run a T from the block feed circuit that is seen in late models.



Parts you will need:
M42 Radiator either used or new from ebay (approx $130; search for “318is radiator”

82 Degree Celsius temp switch; from Bavauto part # 61311364271 approx $17

Most of the hoses are the same; the upper hose can be replaced with: Part number 11531722217 approx $30
The new radiator reservoir feed hose can be taken off the old res and just reconnected or shortened to avoid excess length.

You will need 2 rad support buffers if you don’t have them, they go on the bottom of the rad where it rests on the rad support. Part number : 17111178412 about $2 each, you need 2

You will need one rad support plastic piece, this hold the bottom of the buffer like a cup. The smaller M42 rad requires an extended one because it is not as wide. Part number: 17111712347 about $3.50, you need one. This will replace the rad support on the passenger side, it just snaps in, leave the driver side alone.

2 Gallons of BMW or other phosphate free coolant, mix 50/50 with water

Coolant sensor from e36 with inverted reservoir like the M42 cars, screws into the bottom and connects to your stock late model plug, you will need to extend the wiring about 2 feet to route under the rad. Part #: 61311384739 approx $15 on ebay

A radiator cap; the stock one off your late model coolant res will fit on there without any issues

Electric Fan, I chose a Flex-a-lite model #396. It is a 16 inch reversible fan with S blades. The S blades are considerably quieter then a straight blade fan, you can run this as a pusher (from the front) or a puller (from inside the engine compartment). I chose as a pusher, it is less efficient but cleans up the engine bay nicely. Also pick up some universal mounting brackets for a better install; Flex-a-lite makes some model # 32124. Fan approx $120 brackets $5

I also replaced my thermo with a 75 degree one, any will do 71 for warm climates 75 for moderate and 80 for stock performance. The lower the rated temp, the cooler the engine will run.



Install:

Drain coolant
Remove all hoses
Remove clutch fan: 32mm wrench required
Remove Ac condenser from front of M20 rad support
Remove two 10mm bolts that hold the rad support black plastic bracket in place
Remove temp sensor in side of rad (three prong plug)
Lift out old M20 radiator
Remove coolant res buy pulling up towards windshield and out
If you are doing Timing belt or water pump, this is a good time to do it.
Install passenger side rad support bracket (base of radiator)
Replace thermostat if needed
Install new electric fan utilizing the stock upper AC condenser mount holes and brackets, let wiring hang
Put rubber buffers on bottom of new M42 rad,
Insert e36 coolant level sensor into bottom of new m42 rad
Install new rad into car and secure with stock top bracket
Reconnect lower rad hose and waterpump to thermostat housing hose
Insert single temp switch from Bavauto in side of new rad
Connect only the thermostat housing side of new upper radiator hose.


Wiring:

This is for 88 cabrio (late model wiring) you may be slightly different

Stock AC Fan wiring:
Brown = Ground
Black (at the fan) or Black/Green (after fan connector) = low speed positive feed
Connect your new electric fan Ground to the brown wire, if you cut off the connector connect the positive from your new electric fan to the Black/Green, if you still have the wiring after the connector use the Black.


Thermo switch:
Green/Black = power feed (must be connected)
Black = Low speed relay feed (the one you want to connect to the new thermo switch)
Black/Brown = High speed relay feed (do not connect)
Since your stock themoswitch in the side of the radiator has 3 pins we need to figure out what one will trigger the low speed fan relay to supply power to the new electric fan. You need to put on some spade connectors and connect the Green/Balck to either of the two posts on the back of the new thermoswitch. Then connect the Black line with a spade to the other. Tape off the Black/Brown it is not needed anymore.

The wiring is done in this fashion to allow the stock relays to control the new fan, also if you push the AC switch inside the cabin, you can force on the electric fan anytime you want.



Finishing up:
Since you now have 2 bleeder points it can be a pain to prime and bleed the system.
I found that jacking up the front driver side corner of the car helps a lot to get the system burping up some air bubbles.
Fill your system with the rad cap off and both bleeder screws open and the engine cold. Fill it through the not yet connected upper radiator hose.
When you start to see overflow stop and connect the hose to the upper rad inlet. Also fill the rad resivor unitil it is full.
Start the engine and bring to operating temp, when you thermostat opens the coolant level in the res should drop, now turn on your cabin heat at maximum.
You can squeeze the upper rad hose and the WP to thermostat housing hose to help burp put out some air.
I found that closing off the thermostst housing bleeder then the rad bleeder screw got most of the air out..I then took a 10 min driver up and down some hills and rough roads, then rebled the system until only coolant came from the thermostat bleeder screw.

If you are still having trouble, close the rad bleeder and open the thermostat housing bleeder. Get a short length of 1in rad hose that is clean and take off the rad cap. Blow as hard as possible into the reservoir, this will force the coolant into the block from the bottom and hopefully get you working.

Pat yourself on the back, you are done. Thanks to all the insight from people on R3V helping me figure this out